Dresden 2009 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 25: Fluid dynamics II

DY 25.1: Talk

Thursday, March 26, 2009, 14:45–15:00, ZEU 118

Endwall effects on traveling waves in Taylor-Couette flow — •Kerstin Hochstrate, Matti Heise, Jan Abshagen, and Gerd Pfister — Institute of Experimental and Applied Physics, Kiel, Germany

One of the classical hydrodynamic systems for the study of bifurcation events is the flow consisting of a viscous fluid confined in the gap between two concentric rotating cylinders. Because of the simplicity of this Taylor-Couette experiment the boundary conditions can be controlled and modified precisely. In an infinitely long system, often considered in theoretical investigations, the basic flow consists of a pure azimuthal shear flow which is invariant in the axial direction. In experimental realizations this invariance is broken, because of rigid endplates that confine the flow in the axial direction. At stationary endplates, which are often used, the velocity of the flow is zero. This changes the basic flow and leads to diverse finite-length effects.

Here we analyze experimentally the influence of rotating endplates on the basic flow and on spiral vortex flow. Spirals appear as primary instability for counter-rotating cylinders and travel in the axial direction in the infinite system. In particular, we focus on the interaction of spirals and boundary-driven vortices leading to spatial defects, which are not present in the infinite system. By rotating the endplates these defects can be eliminated and, moreover, the symmetries and the bifurcation behavior of the spirals are influenced.